Copper-based substances with nanomaterials

ABSTRACT

A composition-of-matter is described herein comprising copper or an alloy thereof, and at least one nanocompound dispersed in the copper or an alloy thereof, wherein the copper or an alloy thereof is a cast metal. Further described herein are articles of manufacture comprising the composition-of-matter, and a process for preparing such a composition-of-matter, by dispersing at least one nanocompound in a melt of copper or and alloy thereof, and cooling the melt.

RELATED APPLICATIONS

This application claims the benefit of priority under 35 USC § 119(e) of U.S. Provisional Patent Application No. 62/695,055 filed on Jul. 8, 2018, the contents of which are all incorporated by reference as if fully set forth herein in their entirety.

FIELD AND BACKGROUND OF THE INVENTION

The present invention, in some embodiments thereof, relates to materials science, and more particularly, but not exclusively, to copper-based materials with enhanced mechanical and/or physical properties.

Metal strengthening is one of the main challenges in materials industry. Traditionally, such strengthening is achieved by alloying processes, but high fractions of relatively expensive materials are needed to obtain the desirable technological characteristics.

Copper and its alloys are currently employed in a wide range of engineering applications because of their high ductility, high corrosion resistance, non-magnetic properties, excellent machinability, high hardness and high electrical and thermal conductivity. Copper and its alloys are used extensively in cables, wires, electrical contacts and other components that conduct electrical current. In addition, copper's superior heat transfer capabilities and ability to withstand extreme environments makes it highly suitable for heat exchangers, pressure vessels, vats, and electrical switches.

Copper alloys are primarily strengthened by cold work or by solid solution additions that enhance strain hardening. The addition of alloying elements to copper increases tensile strength, yield strength and the rate of work hardening [Chen et al., J Rare Earths 2014, 32:1056-1063]. Other approaches include grain-size control by annealing [Sarma et al., Mater Sci Eng A 2008, 489:253-258], use of a finely dispersed second phase, or machining processes such as rolling [Das et al., Synthesis and Reactivity in Inorganic, Metal-Organic and Nano-Metal Chemistry 2006, 36:221-225; Okayasu et al., J Sci: Adv Mater Dev 2017, 2:128-139]. However, the addition of a relatively high concentration of costly materials may make such processes economically unfavorable.

Modification of copper or its alloys by adding nanomaterials has been described in the solid phase via a powder metallurgy approach, in which one or more metal powders are fused by sintering. Nano-sized and micro-sized Al₂O₃ particles can be introduced to copper powder by in situ oxidation of copper/aluminum alloy powder or by addition of Al₂O₃ powder to copper powder [Rajkovic et al., J Alloys Comp 2008, 459:177-184; Rajkovic et al., Mater Character 2012, 67:129-137]. Bozic et al. [Bull Mater Sci 2011, 34:217-226] describes copper matrices formed from copper powder with aluminum (which is oxidized to Al₂O₃) or with titanium and titanium diboride (TiB₂). Chu et al. [Mater Des 2013, 45:407-411] reports that sintering of Cu—Cr powders mixed with carbon nanotubes results in enhanced hardness and yield strength relative to pure Cu powder mixed with carbon nanotubes. Kim et al. [Synth Met 2009, 159:424-429] describes copper matrices formed from copper powder mixed with nickel-coated carbon nanotubes. Kim et al. [Appl Phys Lett 2008, 92:121901] describes sintering of carbon nanotube/copper composite powders prepared by dispersing carboxyl-functionalized nanotubes in a copper(II) solution to obtain carbon nanotube/copper oxide composite powders which were then reduced by heating under a hydrogen atmosphere.

Borodianskiy et al. [J Nano Research 2011, 13:41-46] and Borodianskiy et al. [Metall Mat Trans A 2013, 44:4948-4953] describe modification of an aluminum-silicon alloy (A356) with titanium carbide (TiC) nanoparticles, resulting in decreased grain size and improved mechanical properties. Borodianskiy et al. [Metals 2015, 5:2277-2288] describes similar results for aluminum-silicon alloy (A356) modified with titanium carbon nitride (TiCN).

Borodianskiy & Zinigrad [Metall Mat Trans B 2016, 47:1302-1308] describe modification of aluminum and an aluminum-silicon alloy (A356) with tungsten carbide (WC) nanoparticles, resulting in decreased grain size and improved mechanical properties.

The combination of copper with carbon-based materials such as graphite [Mazloum et al., J Mater Sci 2016, 51:7977-7990; Firkowska et al., Nano Lett 2015, 15:4745-4751], diamond [Li et al., Scripta Mater 2015, 109:72-75] or graphene [Wejrzanowski et al., Mater Des 2016, 99:163-173; Gao et al., J Mater Sci Technol 2018, 34:1925-1931] has been researched due to the obtained increase in thermal conductivity.

Barber et al. [Phys Rev Lett 2000, 84:4613-4616] theoretically calculated the thermal conductivity of carbon nanotubes at room temperature to be 6600 W/mK, wherein this relatively high value was attributed to large phonon mean free paths. Samani et al. [Int J Therm Sci 2012, 62:40-43] reported a measured thermal conductivity value of 2586 W/mK for an individual carbon nanotube with a diameter of 150 nm at a room temperature.

Additional background art includes Bai et al. [Composites A 2018, 106:42-51]; Kwon et al. [Comp Sci Technol 2010, 70:546-550]; Liu et al. [Mater Sci Eng A 2019, 739:132-139]; Maki et al. [Scripta Mater 2013, 68:777-780]; Maki et al. [J Sci Adv Mater Dev 2017, 2:128-139]; Özerinç et al. [Scripta Mater 2012, 67:720-723]; Wang et al. [Mater Sci Eng A 2008, 715:163-173]; and Yao [J Mater Sci 2019, 54:4423-4432].

SUMMARY OF THE INVENTION

According to an aspect of some embodiments of the invention, there is provided a composition-of-matter comprising copper or an alloy thereof, and at least one nanocompound dispersed in the copper or an alloy thereof, wherein the copper or an alloy thereof is a cast metal.

According to an aspect of some embodiments of the invention, there is provided a process for preparing a composition-of-matter comprising copper or an alloy thereof, the process comprising dispersing at least one nanocompound in a melt of copper or and alloy thereof, and cooling the melt.

According to an aspect of some embodiments of the invention, there is provided a composition-of-matter prepared according to a process described herein.

According to an aspect of some embodiments of the invention, there is provided an article of manufacture comprising a composition-of-matter described herein.

According to some of any of the embodiments described herein, the composition-of-matter comprises a chill zone, a columnar zone and an equiaxed zone.

According to some of any of the embodiments described herein, the cast metal is a sand-cast metal or a permanent mold-cast metal.

According to some of any of the embodiments described herein, the nanocompound comprises a substance selected from the group consisting of an oxide, a nitride, a carbon nitride, a carbide and/or a carbon-based nanocompound.

According to some of any of the embodiments described herein, the carbon-based nanocompound comprises carbon in a form selected from the group consisting of diamond, graphite, graphene, and a carbon nanotube.

According to some of any of the embodiments described herein, the nanocompound comprises a substance selected from the group consisting of boron nitride, titanium nitride, titanium carbon nitride, titanium carbide, silicon carbide, tungsten carbide, aluminum oxide, titanium oxide, zinc oxide, aluminum diboride, and titanium diboride.

According to some of any of the embodiments described herein, the nanocompound comprises a carbon nanotube and/or an inorganic nanotube, the nanotube being a single-walled or multi-walled nanotube.

According to some of any of the embodiments described herein, the inorganic nanotube comprises a compound selected from the group consisting of tungsten disulfide, molybdenum disulfide, niobium disulfide, tantalum disulfide, hafnium disulfide, titanium disulfide, cadmium sulfide, zinc sulfide, gallium nitride and boron nitride.

According to some of any of the embodiments described herein, the nanotube is a multi-walled nanotube.

According to some of any of the embodiments described herein, a concentration of the nanocompound in the composition-of-matter is in a range of from 0.001 to 1 weight percent (including any intermediate values and subranges therebetween), or from 0.01 to 0.1 weight percent (including any intermediate values and subranges therebetween).

According to some of any of the embodiments described herein, a concentration of the nanocompound in the composition-of-matter is in a range of from 0.001 to 0.015 weight percent (including any intermediate values and subranges therebetween).

According to some of any of the embodiments described herein, the nanocompound is characterized by an average diameter in a range of from 3 to 150 nm (including any intermediate values and subranges therebetween).

According to some of any of the embodiments described herein, the composition-of-matter has a tensile strength which is at least 10% higher than a tensile strength of a corresponding composition-of-matter without the nanocompound (e.g., as determined according to ASTM B 108-01).

According to some of any of the embodiments described herein, the composition-of-matter has a yield strength which is at least 5% higher than a yield strength of a corresponding composition-of-matter without the nanocompound (e.g., as determined according to ASTM B 108-01).

According to some of any of the embodiments described herein, the composition-of-matter has a hardness which is at least 10% higher than a hardness of a corresponding composition-of-matter without the nanocompound, under a load of 10 kg for 10 seconds (e.g., as determined according to a standard Vickers hardness test).

According to some of any of the embodiments described herein, the composition-of-matter has a thermal conductivity which is at least 10% higher than a thermal conductivity a corresponding composition-of-matter without the nanocompound, at a temperature of 25° C. and/or 400° C.

According to some of any of the embodiments described herein, the composition-of-matter has an elongation which is at least 90% of an elongation of a corresponding composition-of-matter without the nanocompound (e.g., as determined according to ASTM B 108-01).

According to some of any of the embodiments described herein, the composition-of-matter has an elongation which is at least 10% higher than a corresponding composition-of-matter without the nanocompound (e.g., as determined according to ASTM B 108-01).

According to some of any of the respective embodiments described herein, the process further comprises effecting mechanochemical mixing of the nanocompound and copper in a solid form prior to dispersing nanocompound in the melt.

According to some of any of the respective embodiments described herein, the copper in a solid form comprises a copper powder.

According to some of any of the respective embodiments described herein, a weight ratio of the nanocompound and the copper in a solid form is in a range of from 1:1 to 1:300 (nanocompound: copper) (including any intermediate values and subranges therebetween), optionally from 1:5 to 1:50 (including any intermediate values and subranges therebetween).

According to some of any of the respective embodiments described herein, the mechanochemical mixing is effected by a ball mill.

According to some of any of the embodiments described herein, the nanocompound is dispersed in the melt at a concentration in a range of from 0.001 to 1 weight percent (including any intermediate values and subranges therebetween), or from 0.01 to 0.1 weight percent (including any intermediate values and subranges therebetween).

According to some of any of the embodiments described herein, the nanocompound is dispersed in the melt at a concentration in a range of from 0.001 to 0.015 weight percent (including any intermediate values and subranges therebetween).

Unless otherwise defined, all technical and/or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the invention, exemplary methods and/or materials are described below. In case of conflict, the patent specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and are not intended to be necessarily limiting.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Some embodiments of the invention are herein described, by way of example only, with reference to the accompanying drawings. With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of embodiments of the invention. In this regard, the description taken with the drawings makes apparent to those skilled in the art how embodiments of the invention may be practiced.

In the drawings:

FIG. 1 presents a schematic illustration showing the dimensions of exemplary specimens of unmodified Cu alloy and of Cu alloy modified with TiN, BN or multi-walled carbon nanotubes (MWCNT) according to some embodiments of the invention (depicted values are in mm units).

FIG. 2 presents a schematic illustration of an exemplary specimen subjected to mechanical property testing according to ASTM B 108-1 (depicted values are in mm units; R6=6 mm radius of curvature).

FIG. 3 presents a stress-strain graph for unmodified Cu alloy and for Cu alloy modified with TiN, BN or multi-walled carbon nanotubes (MWCNT) according to some embodiments of the invention.

FIG. 4 presents a bar graph showing the hardness under a load of 10 kg for 10 seconds (HV₁₀) of unmodified Cu alloy and of Cu alloy modified with TiN, BN or multi-walled carbon nanotubes (MWCNT) according to some embodiments of the invention.

FIG. 5 presents a graph showing thermal conductivity as a function of temperature, for unmodified Cu alloy and for Cu alloy modified with TiN, BN or multi-walled carbon nanotubes (MWCNT) according to some embodiments of the invention.

FIG. 6 presents X-ray powder diffraction patterns of unmodified Cu alloy and of Cu alloy modified with TiN, BN or multi-walled carbon nanotubes (MWCNT) according to some embodiments of the invention.

FIGS. 7A and 7B each present an electron microscopy image of a modifier according to some embodiments of the invention, prepared by mechanochemical treatment of carbon nanotubes with copper.

FIG. 8 presents a stress-strain graph for unmodified Cu alloy and for Cu alloy modified with 0.01, 0.02 or 0.03 weight percent carbon nanotubes (CNT) according to some embodiments of the invention.

FIG. 9 presents a bar graph showing the hardness under a load of 10 kg for 10 seconds (HV₁₀) of unmodified Cu alloy and of Cu alloy modified with 0.01, 0.02 or 0.03 weight percent carbon nanotubes (CNT) according to some embodiments of the invention.

FIGS. 10A and 10B present electron microscopy images of a fracture surface (fractographs) of Cu alloy modified by 0.01% carbon nanotubes (CNT) according to some embodiments of the invention; a single nanotube on the fracture surface is shown in FIG. 10B.

FIGS. 11A and 11B present images of the microstructure of unmodified Cu alloy (FIG. 11A) and Cu alloy modified with 0.01 weight percent carbon nanotubes (CNT) according to some embodiments of the invention (FIG. 11B); the observed outlines of dendritic cells are associated with dissolved oxygen which creates a eutectic phase of cuprous oxide (Cu₂O).

DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION

The present invention, in some embodiments thereof, relates to materials science, and more particularly, but not exclusively, to copper-based materials with enhanced mechanical and/or physical properties.

Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not necessarily limited in its application to the details set forth in the following description or exemplified by the Examples. The invention is capable of other embodiments or of being practiced or carried out in various ways.

Powder metallurgy, in which powders may be blended and then fused by sintering, avoids both the need to melt a metal and the complications associated with solid-liquid phase changes, which would place considerable chemical, thermal and containment restraints on manufacturing. Consequently, powder metallurgy is more flexible than processes involving molten metal, and allows the fabrication of materials which would otherwise decompose or disintegrate.

Nevertheless, the present inventors have envisioned that it would be advantageous to be able to efficiently and reliably modify molten copper or copper alloy with nanomaterials, so as to obtain both the metalworking capabilities of casting and improvements in mechanical properties associated with addition of nanomaterials. The ability to cast molten metals is a significant advantage associated with metals (e.g., in cases where obtaining complex shapes is desired, or in the low-cost mass production by continuous casting of standardized, high-quality metal billets and slabs), and casting remains a widely used technique in metalworking in general, and in copper metalworking in particular. Following laborious experimentation the inventors have surprisingly uncovered that nanomaterials can be dispersed in molten copper (or copper alloy) in a sufficiently homogeneous manner so as to result in enhanced physical properties upon casting.

While reducing the present invention to practice, the present inventors have pretreated a variety of nanomaterials by high-energy milling with copper powder, to form an intermediate “modifier” which, when added to molten copper (or copper alloy), facilitates dispersion of the nanomaterials (as opposed to aggregation and/or floating) in the melt. The exemplary cast copper-based products prepared in this manner were characterized by increases in strength, hardness and thermal conductivity, without exhibiting deleterious changes such as changes in phase composition.

Without being bound by any particular theory, it is believed that convection associated with thermal gradients in the melt further facilitates relatively homogeneous dispersion of the nanomaterials in the melt.

Composition-of-Matter:

According to an aspect of some embodiments of the invention, there is provided a composition-of-matter comprising copper or an alloy thereof, and at least one nanocompound (as defined herein) dispersed in the copper or an alloy thereof, and wherein the copper or an alloy thereof is a cast metal.

As used herein, the phrase “cast metal” refers to a solid metal prepared by cooling of a liquid metal in a mold (which controls the shape of the obtained cast metal). Cast metal may be prepared according to a variety of techniques known in the art, including (without limitation), expendable mold casting, such as sand casting, plaster mold casting, shell casting, and investment casting (e.g., lost-wax casting and/or lost-foam casting); and permanent mold casting (typically with molds made from metal), as described in more detail in the section relating to processes.

The skilled person is capable of distinguishing cast metal from metal prepared via other techniques, using techniques known in the art, e.g., by examining structure of grains (crystals) of the metal.

For example, a cast metal is commonly characterized by a presence of a columnar zone, and optionally also a chill zone and/or equiaxed zone.

Herein, the phrase “columnar zone” refers to a zone, at and/or near a surface of the metal, characterized by grains having the shape of columns, wherein the long axis is perpendicular to an external surface of the metal. Such a zone is believed in the art to be associated with crystallization near the surface (where cooling is more rapid) and gradual growth of crystals inwards, especially crystals with a suitable orientation for inward growth.

Herein, the phrase “chill zone” refers to a zone at the surface of the metal characterized by relatively isotropic crystals, whose width is relatively independent of orientation. Such a zone is believed in the art to be associated with nucleation of crystals the surface, where rapid cooling occurs (e.g., upon contact with a mold used in casting).

Herein, the phrase “equiaxed zone” refers to a zone at an internal portion of the metal (e.g., separated from the surface by at least a columnar zone) characterized by relatively isotropic crystals, whose width is relatively independent of orientation, and whose orientations are relatively random. The mechanism by which an equiaxed zone is formed is debated in the art, but it may be associated with detachment of crystals from the surface followed by gradual growth as the inner portion of the molten metal slowly cools.

Herein, the term “alloy” refers to a mixture or solid solution composed of a metal (e.g., copper) and one or more other chemical elements, at any molar ratio of metal to the other chemical element(s). When more than one other chemical element is present in the alloy (in addition to the aforementioned metal), such chemical elements may be in a form of a mixture of individual chemical elements and/or in a form of at least one chemical compound (i.e., a substance composed of atoms of more than one chemical element attached to each other via covalent or noncovalent bonds).

Herein, an “alloy” of copper refers to an alloy, as defined herein, wherein copper is the most abundant metal therein (by weight). It is to be appreciated that alloys of copper which comprise a sufficiently high percentage of copper may also be regarded simply as copper with a conventional amount of impurities.

In some embodiments of any of the respective embodiments described herein, the alloy of copper is at least 50% copper by weight. In some embodiments, the alloy of copper is at least 60% copper by weight. In some embodiments, the alloy of copper is at least 70% copper by weight. In some embodiments, the alloy of copper is at least 80% copper by weight. In some embodiments, the alloy of copper is at least 90% copper by weight. In some embodiments, the alloy of copper is at least 95% copper by weight. In some embodiments, the alloy of copper is at least 98% copper by weight. In some embodiments, the alloy of copper is at least 99% copper by weight. In some embodiments, the alloy of copper is at least 99.5% copper by weight. In some embodiments, the alloy of copper is at least 99.8% copper by weight. In some embodiments, the alloy of copper is at least 99.9% copper by weight.

In some embodiments of any of the embodiments described herein, the composition-of-matter is characterized by enhancement of one or more mechanical properties (e.g., tensile strength, yield strength, hardness and/or elongation) or physical properties (e.g., thermal conduction and/or electrical conduction), in comparison with a corresponding composition-of-matter being composed of the same ingredients (e.g., copper or alloy thereof) and preferably prepared in the same manner, except for being without the nanocompound(s) described herein.

Determination of mechanical properties (e.g., tensile strength, yield strength, hardness and/or elongation) may optionally be effected according to standard procedures known in the art, for example, according to ASTM B 108-01. Alternatively or additionally, hardness may be determined according to a standard Vickers hardness test, as known in the art, under a load of 10 kg for 10 seconds.

Determination of thermal conduction may optionally be effected on coupons (e.g., 10 mm×10 mm coupons with a thickness of 5 mm) using a laser flash analyzer, preferably under an inert (e.g., argon) atmosphere.

Determination of mechanical properties (e.g., tensile strength, yield strength, hardness and/or elongation) or thermal conduction may optionally be effected according to procedures exemplified herein, e.g., optionally at ambient temperature (e.g., 25° C.).

In some embodiments of any of the embodiments described herein, the composition-of-matter has a higher tensile strength than does a corresponding composition-of-matter without the nanocompound (under the same conditions, e.g., temperature), e.g., as determined according to ASTM B 108-01. In some embodiments, the composition-of-matter has a tensile strength which is at least 10% higher than a tensile strength of a corresponding composition-of-matter without the nanocompound. In some embodiments, the composition-of-matter has a tensile strength which is at least 15% higher than a tensile strength of a corresponding composition-of-matter without the nanocompound. In some embodiments, the composition-of-matter has a tensile strength which is at least 20% higher than a tensile strength of a corresponding composition-of-matter without the nanocompound. In some embodiments, the composition-of-matter has a tensile strength which is at least 25% higher than a tensile strength of a corresponding composition-of-matter without the nanocompound.

In some embodiments of any of the embodiments described herein, the composition-of-matter has a tensile strength which is at least 200 MPa (e.g., as determined according to ASTM B 108-01). In some such embodiments, the tensile strength is at least 210 MPa. In some embodiments, the tensile strength is at least 220 MPa. In some embodiments, the tensile strength is at least 230 MPa. In some embodiments, the tensile strength is at least 240 MPa. In some embodiments, a tensile strength of a corresponding composition-of-matter without the nanocompound is less than 200 MPa, and optionally less than 190 MPa.

Herein, the phrase “tensile strength” is equal to the maximal degree of tensile stress to which a material is subjected, as the material is gradually subjected to increasing strain (e.g., the highest point on a stress-strain curve plotting stress as a function of strain) due to tension (being pulled apart). The maximal stress may occur at the point of rupture, or alternatively, maximal stress may be followed by decreasing stress as strain increases (a phenomenon known in the art as “necking”).

In some embodiments of any of the embodiments described herein, the composition-of-matter has a higher yield strength than does a corresponding composition-of-matter without the nanocompound (under the same conditions, e.g., temperature), e.g., as determined according to ASTM B 108-01. In some embodiments, the composition-of-matter has a yield strength which is at least 5% higher than a yield strength of a corresponding composition-of-matter without the nanocompound. In some embodiments, the composition-of-matter has a yield strength which is at least 7% higher than a yield strength of a corresponding composition-of-matter without the nanocompound. In some embodiments, the composition-of-matter has a yield strength which is at least 9% higher than a yield strength of a corresponding composition-of-matter without the nanocompound. In some embodiments, the composition-of-matter has a yield strength which is at least 11% higher than a yield strength of a corresponding composition-of-matter without the nanocompound. In some embodiments, the composition-of-matter has a yield strength which is at least 13% higher than a yield strength of a corresponding composition-of-matter without the nanocompound. In some embodiments, the composition-of-matter has a yield strength which is at least 15% higher than a yield strength of a corresponding composition-of-matter without the nanocompound.

In some embodiments of any of the embodiments described herein, the composition-of-matter has a yield strength which is at least 54 MPa (e.g., as determined according to ASTM B 108-01). In some such embodiments, the yield strength is at least 56 MPa. In some embodiments, the yield strength is at least 58 MPa. In some embodiments, the yield strength is at least 60 MPa. In some embodiments, a yield strength of a corresponding composition-of-matter without the nanocompound is less than 55 MPa, and optionally less than 54 MPa.

Herein, the phrase “yield strength” is equal to the maximal degree of tensile stress to which a material is subjected, as the material is gradually subjected to increasing strain (e.g., the highest point on a stress-strain curve plotting stress as a function of strain) due to tension (being pulled apart), until plastic deformation (i.e., deformation which is non-reversible upon removal of the stress) begins to occur.

In some embodiments of any of the embodiments described herein, the composition-of-matter has a higher hardness than does a corresponding composition-of-matter without the nanocompound (under the same conditions, e.g., temperature), e.g., as determined according to a standard Vickers test under a load of 10 kg for 10 seconds. In some embodiments, the composition-of-matter has a hardness which is at least 10% higher than a hardness of a corresponding composition-of-matter without the nanocompound. In some embodiments, the composition-of-matter has a hardness which is at least 15% higher than a hardness of a corresponding composition-of-matter without the nanocompound. In some embodiments, the composition-of-matter has a hardness which is at least 20% higher than a hardness of a corresponding composition-of-matter without the nanocompound. In some embodiments, the composition-of-matter has a hardness which is at least 25% higher than a hardness of a corresponding composition-of-matter without the nanocompound. In some embodiments, the composition-of-matter has a hardness which is at least 30% higher than a hardness of a corresponding composition-of-matter without the nanocompound. In some embodiments, the composition-of-matter has a hardness which is at least 35% higher than a hardness of a corresponding composition-of-matter without the nanocompound. In some embodiments, the composition-of-matter has a hardness which is at least 40% higher than a hardness of a corresponding composition-of-matter without the nanocompound. In some embodiments, the composition-of-matter has a hardness which is at least 45% higher than a hardness of a corresponding composition-of-matter without the nanocompound. In some embodiments, the composition-of-matter has a hardness which is at least 50% higher than a hardness of a corresponding composition-of-matter without the nanocompound. In some embodiments, the composition-of-matter has a hardness which is at least 60% higher than a hardness of a corresponding composition-of-matter without the nanocompound. In some embodiments, the composition-of-matter has a hardness which is at least 70% higher than a hardness of a corresponding composition-of-matter without the nanocompound. In some embodiments, the composition-of-matter has a hardness which is at least 80% higher than a hardness of a corresponding composition-of-matter without the nanocompound. In some embodiments, the composition-of-matter has a hardness which is at least 90% higher than a hardness of a corresponding composition-of-matter without the nanocompound. In some embodiments, the composition-of-matter has a hardness which is at least 100% higher than (i.e., two-fold) a hardness of a corresponding composition-of-matter without the nanocompound. In some embodiments, the composition-of-matter has a hardness which is at least 150% higher than a hardness of a corresponding composition-of-matter without the nanocompound. In some embodiments, the composition-of-matter has a hardness which is at least 200% higher than (i.e., three-fold) a hardness of a corresponding composition-of-matter without the nanocompound.

Herein, the term “hardness” refers to resistance of a material to indentation upon being subjected to a compression load. The specific conditions under which hardness is determined may be, for example, as defined for a Rockwell hardness test, a Vickers hardness test, a Shore hardness test, or a Brinell hardness test.

In some embodiments, hardness is determined under a load of 10 kg for 10 seconds.

In exemplary embodiments, the hardness is determined by a Vickers hardness test (which uses a diamond indenter of a defined shape). As known in the art, the hardness according to a Vickers test (referred to interchangeably as “HV” or “Vickers hardness”) is approximately equal to 0.1891*F/d², wherein F is the applied force in kg (e.g., 10 kg), and d is the average length (in mm) of a diagonal of the indentation.

In some embodiments of any of the embodiments described herein, the composition-of-matter has a Vickers hardness (determined under a load of 10 kg for 10 seconds) which is at least 45. In some such embodiments, the Vickers hardness is at least 50. In some such embodiments, the Vickers hardness is at least 60. In some such embodiments, the Vickers hardness is at least 70. In some such embodiments, the Vickers hardness is at least 80. In some such embodiments, the Vickers hardness is at least 90. In some such embodiments, the Vickers hardness is at least 100.

In some embodiments, a Vickers hardness (determined under a load of 10 kg for 10 seconds) of a corresponding composition-of-matter without the nanocompound is less than 45, and optionally less than 40.

Herein, the term “elongation” refers to a ratio (optionally expressed as a percentage) of a maximal increase in length of a material (i.e., the increase at rupture) to an initial length of the material, upon being subjected to tensile stress. A higher degree of elongation will typically reflect resistance to rupture under strain.

Without being bound by any particular theory, it is believed that increases in tensile strength in materials is usually accompanied by a decrease in elongation, such that it would be advantageous for a composition-of-matter described herein (e.g., a composition-of-matter having an enhanced tensile strength) according to any of the respective embodiments described herein to exhibit even an elongation which is only slightly lower than (or even higher than) an elongation of a corresponding composition-of-matter without the nanocompound (under the same conditions, e.g., temperature). It is further believed that it would be especially advantageous for a composition-of-matter described herein (e.g., a composition-of-matter having an enhanced tensile strength) according to any of the respective embodiments described herein to have an elongation which is higher than an elongation of a corresponding composition-of-matter without the nanocompound.

In some embodiments of any of the embodiments described herein, the composition-of-matter has an elongation which is at least 80% of (i.e., no more than 20% less than) an elongation of a corresponding composition-of-matter without the nanocompound (e.g., as determined according to ASTM B 108-01). In some such embodiments, the composition-of-matter has an elongation which is at least 90% of (i.e., no more than 10% less than) that of a corresponding composition-of-matter without the nanocompound.

In some embodiments, the composition-of-matter has an elongation which is at least as high as that of a corresponding composition-of-matter without the nanocompound (e.g., as determined according to ASTM B 108-01). In some embodiments, the composition-of-matter has an elongation which is at least 10% higher than (i.e., 110% of) that of a corresponding composition-of-matter without the nanocompound. In some embodiments, the composition-of-matter has an elongation which is at least 20% higher than (i.e., 120% of) that of a corresponding composition-of-matter without the nanocompound. In some embodiments, the composition-of-matter has a tensile strength which is higher than that of a corresponding composition-of-matter without the nanocompound, according to any of the respective embodiments described herein.

In some embodiments of any of the embodiments described herein, the composition-of-matter has an elongation which is at least 30% (e.g., as determined according to ASTM B 108-01). In some embodiments, the elongation is at least 35%. In some embodiments, the elongation is at least 40%. In some embodiments, the elongation is at least 50%. In some embodiments, the composition-of-matter has a tensile strength which is higher than that of a corresponding composition-of-matter without the nanocompound, according to any of the respective embodiments described herein.

In some embodiments of any of the embodiments described herein, the composition-of-matter has a higher thermal conductivity than does a corresponding composition-of-matter without the nanocompound (under the same conditions, e.g., temperature). In some embodiments, the composition-of-matter has a thermal conductivity which is at least 10% higher than a thermal conductivity of a corresponding composition-of-matter without the nanocompound. In some embodiments, the composition-of-matter has a thermal conductivity which is at least 20% higher than a thermal conductivity of a corresponding composition-of-matter without the nanocompound. In some embodiments, the composition-of-matter has a thermal conductivity which is at least 30% higher than a thermal conductivity of a corresponding composition-of-matter without the nanocompound. In some embodiments, the composition-of-matter has a thermal conductivity which is at least 40% higher than a thermal conductivity of a corresponding composition-of-matter without the nanocompound. In some embodiments, the composition-of-matter has a thermal conductivity which is at least 50% higher than a thermal conductivity of a corresponding composition-of-matter without the nanocompound.

Herein and in the art, thermal conductivity is expressed in units of power per distance per temperature, for example, in units of watts per meter-kelvin, referred to herein interchangeably as “W/mK” and “W/(m·K)”.

A thermal conductivity (according to any of the respective embodiments described herein) may optionally be determined at a temperature in a range of from 0-500° C. (including any intermediate values and subranges therebetween), for example, at 25° C., 100° C., 200° C., 300° C. and/or 400° C. In some of any of the respective embodiments, the composition-of-matter has a thermal conductivity as described herein at a temperature of 25° C. and/or 400° C. In some of any of the respective embodiments, the composition-of-matter has a thermal conductivity as described herein at both 25° C. and 400° C.

In some embodiments of any of the embodiments described herein, the composition-of-matter has a thermal conductivity (at 25° C. and/or 400° C.) which is at least 320 W/mK. In some such embodiments, the thermal conductivity (at 25° C. and/or 400° C.) is at least 340 W/mK. In some embodiments, the thermal conductivity (at 25° C. and/or 400° C.) is at least 360 W/mK. In some embodiments, the thermal conductivity (e.g., at 25° C.) is at least 380 W/mK. In some embodiments, the thermal conductivity (e.g., at 25° C.) is at least 400 W/mK. In some embodiments, the thermal conductivity (e.g., at 25° C.) is at least 440 W/mK. In some embodiments, the thermal conductivity (e.g., at 25° C.) is at least 460 W/mK. In some embodiments, a thermal conductivity (at 25° C. and/or 400° C.) of a corresponding composition-of-matter without the nanocompound is less than 320 W/mK. In some embodiments, a thermal conductivity (e.g., at 400° C.) of a corresponding composition-of-matter without the nanocompound is less than 300 W/mK. In some embodiments, the thermal conductivity (e.g., at 400° C.) of the corresponding composition-of-matter without the nanocompound is less than 280 W/mK. In some embodiments, the thermal conductivity (e.g., at 400° C.) of the corresponding composition-of-matter without the nanocompound is less than 260 W/mK.

In some embodiments of any of the embodiments described herein, the composition-of-matter is prepared according to a process described herein, according to any of the respective embodiments.

According to an aspect of some embodiments of the invention there is provided an article of manufacture comprising a composition-of-matter according to any of the respective embodiments described herein.

Examples of suitable articles of manufacture in which a copper-containing composition-of-matter can be incorporated include, without limitation, electronic devices (e.g., electrical switches, integrated circuits, printed circuit boards, electric motors) comprising the composition-of matter in cables, wires, electrical contacts and/or other conducting components; radiofrequency shielding; heat sinks and heat exchangers; containers (e.g., pressure vessels or vats) for use at high temperature, and other devices (e.g., electromagnets, magnetrons, vacuum tubes, cathode ray tubes) which normally heat up during use; and/or structural (e.g., architectural) components (e.g., where corrosion resistance is particularly important), such as roofing, gutters, pipes (e.g., drain pipes), decorative structures (e.g., domes, spires), wall cladding, building expansion joints, railing, plumbing fixtures, and counter tops.

In articles of manufacture in which exposure to heat upon use is normal, such as heat sinks and heat exchangers; containers for use at high temperature, and other devices (e.g., electronic devices) which normally heat up during use (according to any of the respective embodiments described herein), the composition-of-matter contained therein optionally exhibit an enhanced thermal conductivity (relative to a corresponding composition-of-matter without a nanocompound) according to any of the respective embodiments described herein.

In articles of manufacture in which are structural (e.g., architectural) components, the composition-of-matter contained therein optionally exhibit at least one enhanced mechanical property (relative to a corresponding composition-of-matter without a nanocompound) according to any of the respective embodiments described herein.

Nanocompound:

Herein, the term “nanocompound” refers to a compound or substance in a form characterized by an average width of less than 1 μm along at least one dimension thereof. Thus, the term “nanocompound” encompasses particles with a diameter of less than 1 μm (e.g., in any direction), tubes (referred to herein as “nanotubes”) with a width of less than 1 μm (but optionally longer than 1 μm along the long axis of the tube), and sheets with a width of less than 1 μm along an axis perpendicular to the plane of the sheet (but optionally longer than with a width of less than 1 μm, along two axes in the plane of the sheet).

Herein, the term “nanoparticle” refers to any particle of a nanocompound, as defined herein, and encompasses particles of any possible shape, including tubes and sheets. Although the term “nanoparticle” may be most frequently used to refer to particles having a shape other than a tube or a sheet (e.g., particles whose width is relatively equal in different directions), this usage is not to be considered limiting unless explicitly stated otherwise.

In some embodiments of any of the embodiments described herein, the nanocompound is characterized by an average diameter of no more than 150 nm, for example, in a range of from 3 to 150 nm, or from 5 to 150 nm, or from 10 to 150 nm (including any intermediate values and subranges therebetween). In some embodiments, the average diameter is no more than 100 nm, for example, in a range of from 3 to 100 nm, or from 5 to 100 nm, or from 10 to 100 nm (including any intermediate values and subranges therebetween). In some embodiments, the average diameter is no more than 50 nm, for example, in a range of from 3 to 50 nm, or from 5 to 50 nm, or from 10 to 50 nm (including any intermediate values and subranges therebetween).

In some embodiments, the nanocompound comprises nanoparticles with an average diameter (e.g., an average diameter of nanoparticles in all dimensions) of no more than 30 nm, for example, in a range of from 3 to 30 nm, or from 5 to 30 nm, or from 10 to 30 nm (including any intermediate values and subranges therebetween).

In some embodiments, the nanocompound comprises nanotubes, and the average diameter of the nanotubes (i.e., a cross-section the nanotubes) is no more than 75 nm, for example, in a range of from 5 nm to 75 nm, or from 10 nm to 75 nm, or from 25 nm to 75 nm (including any intermediate values and subranges therebetween). In some embodiments, the average diameter is no more than 50 nm, for example, in a range of from 5 nm to 50 nm, or from 10 nm to 50 nm, or from 30 nm to 50 nm (including any intermediate values and subranges therebetween).

The phrase “average diameter” herein encompasses averages of diameters of a nanoparticle in all dimensions thereof, as well as averages of diameters of a two-dimensional cross-section of nanotubes.

In some embodiments of any of the embodiments described herein, the nanocompound comprises a substance which is an oxide, a nitride, a carbon nitride, a carbide and/or a carbon-based nanocompound. In some embodiments, the substance is a metal oxide, a metal nitride, a metal carbon nitride, and/or a metal carbide.

Herein, the term “nitride” refers to a compound composed of nitrogen and a less electronegative element (e.g., a metal).

Examples of nitrides suitable for inclusion in a nanocompound include, without limitation, boron nitride and titanium nitride.

Herein, the term “carbon nitride” refers to a compound composed of carbon and nitrogen with a less electronegative element (e.g., a metal).

Titanium carbon nitride is a non-limiting example of a carbon nitride suitable for inclusion in a nanocompound.

Herein, the term “carbide” refers to a compound composed of carbon and a less electronegative element (e.g., a metal).

Examples of carbides suitable for inclusion in a nanocompound include, without limitation, titanium carbide, silicon carbide, and tungsten carbide.

Examples of oxides suitable for inclusion in a nanocompound include, without limitation, aluminum oxide, titanium oxide, and zinc oxide.

Additional examples of substances suitable for inclusion in a nanocompound include, without limitation, borides such as aluminum diboride (AlB₂), and titanium diboride (TiB₂).

Examples of carbon-based nanocompounds include, without limitation, diamond nanocompound, graphite nanocompound, graphene nanocompound, and carbon nanotubes. Carbon nanotubes are exemplary carbon-based nanocompounds.

In some embodiments of any of the embodiments described herein, the nanocompound comprises a carbon nanotube and/or an inorganic nanotube. The nanotubes may optionally be single-walled or multi-walled nanotubes. In exemplary embodiments, the nanotubes are multi-walled nanotubes.

Examples of compounds which may be comprised by inorganic nanotubes include, without limitation, tungsten disulfide, molybdenum disulfide, niobium disulfide, tantalum disulfide, hafnium disulfide, titanium disulfide, cadmium sulfide, zinc sulfide, gallium nitride and boron nitride.

In some embodiments of any of the embodiments described herein, a concentration of the nanocompound(s) in the composition-of-matter is at least 0.001 weight percent. In some embodiments, the concentration of nanocompound(s) in the composition-of-matter is in a range of from 0.001 to 1 weight percent (including any intermediate values and subranges therebetween). In some embodiments, the concentration of nanocompound(s) in the composition-of-matter is in a range of from 0.001 to 0.3 weight percent (including any intermediate values and subranges therebetween). In some embodiments, the concentration of nanocompound(s) in the composition-of-matter is in a range of from 0.001 to 0.1 weight percent (including any intermediate values and subranges therebetween). In some embodiments, the concentration of nanocompound(s) in the composition-of-matter is in a range of from 0.001 to 0.03 weight percent (including any intermediate values and subranges therebetween). In some embodiments, the concentration of nanocompound(s) in the composition-of-matter is in a range of from 0.001 to 0.025 weight percent (including any intermediate values and subranges therebetween). In some embodiments, the concentration of nanocompound(s) in the composition-of-matter is in a range of from 0.001 to 0.02 weight percent (including any intermediate values and subranges therebetween). In some embodiments, the concentration of nanocompound(s) in the composition-of-matter is in a range of from 0.001 to 0.015 weight percent (including any intermediate values and subranges therebetween). In some such embodiments, the nanocompound comprises a carbon-based nanocompound, for example, carbon nanotubes (according to any of the respective embodiments described herein).

In some embodiments of any of the embodiments described herein, a concentration of the nanocompound(s) in the composition-of-matter is at least 0.003 weight percent. In some embodiments, the concentration of nanocompound(s) in the composition-of-matter is in a range of from 0.003 to 1 weight percent (including any intermediate values and subranges therebetween). In some embodiments, the concentration of nanocompound(s) in the composition-of-matter is in a range of from 0.003 to 0.3 weight percent (including any intermediate values and subranges therebetween). In some embodiments, the concentration of nanocompound(s) in the composition-of-matter is in a range of from 0.003 to 0.1 weight percent (including any intermediate values and subranges therebetween). In some embodiments, the concentration of nanocompound(s) in the composition-of-matter is in a range of from 0.003 to 0.03 weight percent (including any intermediate values and subranges therebetween). In some embodiments, the concentration of nanocompound(s) in the composition-of-matter is in a range of from 0.003 to 0.025 weight percent (including any intermediate values and subranges therebetween). In some embodiments, the concentration of nanocompound(s) in the composition-of-matter is in a range of from 0.003 to 0.02 weight percent (including any intermediate values and subranges therebetween). In some embodiments, the concentration of nanocompound(s) in the composition-of-matter is in a range of from 0.003 to 0.015 weight percent (including any intermediate values and subranges therebetween). In some such embodiments, the nanocompound comprises a carbon-based nanocompound, for example, carbon nanotubes (according to any of the respective embodiments described herein).

In some embodiments of any of the embodiments described herein, a concentration of the nanocompound(s) in the composition-of-matter is at least 0.01 weight percent. In some embodiments, the concentration of nanocompound(s) in the composition-of-matter is in a range of from 0.01 to 1 weight percent (including any intermediate values and subranges therebetween). In some embodiments, the concentration of nanocompound(s) in the composition-of-matter is in a range of from 0.01 to 0.3 weight percent (including any intermediate values and subranges therebetween). In some embodiments, the concentration of nanocompound(s) in the composition-of-matter is in a range of from 0.01 to 0.1 weight percent (including any intermediate values and subranges therebetween). In some embodiments, the concentration of nanocompound(s) in the composition-of-matter is in a range of from 0.01 to 0.03 weight percent (including any intermediate values and subranges therebetween). In some embodiments, the concentration of nanocompound(s) in the composition-of-matter is in a range of from 0.01 to 0.025 weight percent (including any intermediate values and subranges therebetween). In some embodiments, the concentration of nanocompound(s) in the composition-of-matter is in a range of from 0.01 to 0.02 weight percent (including any intermediate values and subranges therebetween). In some such embodiments, the nanocompound comprises a carbon-based nanocompound, for example, carbon nanotubes (according to any of the respective embodiments described herein).

In some embodiments of any of the embodiments described herein, a concentration of the nanocompound(s) in the composition-of-matter is at least 0.03 weight percent. In some embodiments, the concentration of nanocompound(s) in the composition-of-matter is in a range of from 0.03 to 1 weight percent (including any intermediate values and subranges therebetween). In some embodiments, the concentration of nanocompound(s) in the composition-of-matter is in a range of from 0.03 to 0.3 weight percent (including any intermediate values and subranges therebetween). In some embodiments, the concentration of nanocompound(s) in the composition-of-matter is in a range of from 0.03 to 0.1 weight percent (including any intermediate values and subranges therebetween).

Process:

According to an aspect of some embodiments of the invention, there is provided a process for preparing a composition-of-matter comprising copper or an alloy thereof (e.g., according to any of the embodiments described herein relating to a composition-of-matter). The process comprising dispersing at least one nanocompound (according to any of the respective embodiments described herein) in a melt of copper or and alloy thereof, and cooling the melt.

In some embodiments of any of the embodiments described herein, the process further comprises effecting mechanochemical mixing of the nanocompound and copper in a solid form prior to dispersing the nanocompound in a melt (according to any of the respective embodiments described herein). The copper in solid form may be, for example, a bulk form, a foil, a granulate and/or a powder. In exemplary embodiments, the copper in solid form comprises a copper powder.

Herein, the phrase “mechanochemical mixing” refers to a chemical mixing of two or more substances (e.g., to form a composite material) which is effected by mechanical force.

Mechanochemical mixing of the nanocompound and copper may optionally be effected by any apparatus and/or technique suitable for applying considerable mechanical force, including, for example, milling, pressing and/or extrusion. In exemplary embodiments, mechanochemical mixing is effected by a ball mill (e.g., mixing of nanocompounds with a copper powder).

Mechanochemical mixing may optionally be effected so as to obtain a substance (comprising the copper in solid form, as described herein) having a higher amount of nanocompound than intended in the product to be obtained by the process. Such a substance (also referred to herein as a “modifier”) may optionally be combined in a melt (according to any of the respective embodiments described herein) with additional copper (or alloy thereof), thereby diluting and dispersing the nanocompound at the desired concentration, for example, a nanocompound concentration in a composition-of-matter according to any of the respective embodiments described herein.

In some embodiments of any of the embodiments described herein, an amount of nanocompound(s) and copper subjected to mechanochemical mixing is such that a weight ratio of the nanocompound(s) to the copper (in solid form) is at least 1:300 (nanocompound: copper). In some embodiments, the weight ratio is in a range of from 1:300 to 1:1 (nanocompound: copper) (including any intermediate values and subranges therebetween). In some embodiments, the weight ratio is in a range of from 1:300 to 1:2 (nanocompound: copper) (including any intermediate values and subranges therebetween). In some embodiments, the weight ratio is in a range of from 1:300 to 1:5 (nanocompound: copper) (including any intermediate values and subranges therebetween). In some embodiments, the weight ratio is in a range of from 1:300 to 1:10 (nanocompound: copper) (including any intermediate values and subranges therebetween). In some embodiments, the weight ratio is in a range of from 1:300 to 1:20 (nanocompound: copper) (including any intermediate values and subranges therebetween). In some embodiments, the weight ratio is in a range of from 1:300 to 1:50 (nanocompound: copper) (including any intermediate values and subranges therebetween).

In some embodiments of any of the embodiments described herein, an amount of nanocompound(s) and copper subjected to mechanochemical mixing is such that a weight ratio of the nanocompound(s) to the copper (in solid form) is at least 1:100 (nanocompound: copper). In some embodiments, the weight ratio is in a range of from 1:100 to 1:1 (nanocompound: copper) (including any intermediate values and subranges therebetween). In some embodiments, the weight ratio is in a range of from 1:100 to 1:2 (nanocompound: copper) (including any intermediate values and subranges therebetween). In some embodiments, the weight ratio is in a range of from 1:100 to 1:5 (nanocompound: copper) (including any intermediate values and subranges therebetween). In some embodiments, the weight ratio is in a range of from 1:100 to 1:10 (nanocompound: copper) (including any intermediate values and subranges therebetween). In some embodiments, the weight ratio is in a range of from 1:100 to 1:20 (nanocompound: copper) (including any intermediate values and subranges therebetween). In some embodiments, the weight ratio is in a range of from 1:100 to 1:50 (nanocompound: copper) (including any intermediate values and subranges therebetween).

In some embodiments of any of the embodiments described herein, an amount of nanocompound(s) and copper subjected to mechanochemical mixing is such that a weight ratio of the nanocompound(s) to the copper (in solid form) is at least 1:50 (nanocompound: copper). In some embodiments, the weight ratio is in a range of from 1:50 to 1:1 (nanocompound: copper) (including any intermediate values and subranges therebetween). In some embodiments, the weight ratio is in a range of from 1:50 to 1:2 (nanocompound: copper) (including any intermediate values and subranges therebetween). In some embodiments, the weight ratio is in a range of from 1:50 to 1:5 (nanocompound: copper) (including any intermediate values and subranges therebetween). In some embodiments, the weight ratio is in a range of from 1:50 to 1:10 (nanocompound: copper) (including any intermediate values and subranges therebetween). In some embodiments, the weight ratio is in a range of from 1:50 to 1:20 (nanocompound: copper) (including any intermediate values and subranges therebetween).

In some embodiments of any of the embodiments described herein, an amount of nanocompound(s) and copper subjected to mechanochemical mixing is such that a weight ratio of the nanocompound(s) to the copper (in solid form) is at least 1:20 (nanocompound: copper). In some embodiments, the weight ratio is in a range of from 1:20 to 1:1 (nanocompound: copper) (including any intermediate values and subranges therebetween). In some embodiments, the weight ratio is in a range of from 1:20 to 1:2 (nanocompound: copper) (including any intermediate values and subranges therebetween). In some embodiments, the weight ratio is in a range of from 1:20 to 1:5 (nanocompound: copper) (including any intermediate values and subranges therebetween). In some embodiments, the weight ratio is in a range of from 1:20 to 1:10 (nanocompound: copper) (including any intermediate values and subranges therebetween).

In some embodiments of any of the embodiments described herein, an amount of nanocompound(s) and copper subjected to mechanochemical mixing is such that a weight ratio of the nanocompound(s) to the copper (in solid form) is at least 1:10 (nanocompound: copper). In some embodiments, the weight ratio is in a range of from 1:10 to 1:1 (nanocompound: copper) (including any intermediate values and subranges therebetween). In some embodiments, the weight ratio is in a range of from 1:10 to 1:2 (nanocompound: copper) (including any intermediate values and subranges therebetween). In some embodiments, the weight ratio is in a range of from 1:10 to 1:5 (nanocompound: copper) (including any intermediate values and subranges therebetween).

The melt (according to any of the respective embodiments described herein) may be cooled in a mold, so as to obtain a cast metal, using a suitable metal casting technique known in the art.

The mold may optionally be an expendable mold, such as a sand mold (typically formed from a suitable types of sand bonded by clay or oil) for sand casting, a plaster mold for plaster mold casting, a shell mold (typically formed from fine sand and a resin) for shell mold casting, plaster mold casting, shell casting, a wax mold for lost-wax casting, or a foam mold (e.g., comprising polystyrene foam) for lost-foam casting.

Alternatively or additionally, the mold may optionally be a permanent mold (made from metal or graphite) for permanent mold casting.

The melt may optionally be inserted into the mold by gravity, and/or by pressure (e.g., gas pressure pushing the melt into the mold, vacuum sucking the melt into the mold, and/or centrifugal force for pushing the melt into peripheral portions of the mold), for example, as in die casting. The melt may optionally be evacuated from the mold (e.g., by gravity), for example, in slush casting (which results in a hollow cast metal object) and/or in continuous casting (in which a product such as a metal strip, ingot, billet or slab exits the mold while melt is still entering another side of the mold).

It is expected that during the life of a patent maturing from this application many relevant casting techniques will be developed and the scope of the terms “casting” and “cast metal” is intended to include all such new technologies a priori.

According to an aspect of some embodiments of the invention, there is provided a method for enhancing one or more properties of copper or a copper alloy, the method comprising adding a nanocompound to the copper or alloy thereof, according to a process of any of the respective embodiments described herein (e.g., so as to obtain a composition-of-matter according to any of the respective embodiments described herein). The one or more enhanced properties (and the degree of enhancement) may optionally be an enhanced mechanical property or thermal conductivity according to any of the respective embodiments described herein.

The terms “comprises”, “comprising”, “includes”, “including”, “having” and their conjugates mean “including but not limited to”.

The term “consisting of” means “including and limited to”.

The term “consisting essentially of” means that the composition, method or structure may include additional ingredients, steps and/or parts, but only if the additional ingredients, steps and/or parts do not materially alter the basic and novel characteristics of the claimed composition, method or structure.

As used herein, the singular form “a”, “an” and “the” include plural references unless the context clearly dictates otherwise. For example, the term “a compound” or “at least one compound” may include a plurality of compounds, including mixtures thereof.

Throughout this application, various embodiments of this invention may be presented in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the invention. Accordingly, the description of a range should be considered to have specifically disclosed all the possible subranges as well as individual numerical values within that range. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within that range, for example, 1, 2, 3, 4, 5, and 6. This applies regardless of the breadth of the range.

Whenever a numerical range is indicated herein, it is meant to include any cited numeral (fractional or integral) within the indicated range. The phrases “ranging/ranges between” a first indicate number and a second indicate number and “ranging/ranges from” a first indicate number “to” a second indicate number are used herein interchangeably and are meant to include the first and second indicated numbers and all the fractional and integral numerals therebetween.

It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination or as suitable in any other described embodiment of the invention. Certain features described in the context of various embodiments are not to be considered essential features of those embodiments, unless the embodiment is inoperative without those elements.

Various embodiments and aspects of the present invention as delineated hereinabove and as claimed in the claims section below find experimental support in the following examples.

EXAMPLES

Reference is now made to the following examples, which together with the above descriptions illustrate some embodiments of the invention in a non-limiting fashion.

Materials and Methods

Materials:

Boron nitride (BN) and titanium nitride (TiN) nanoparticles were obtained from IoLiTec Ionic Liquids Technologies GmbH (Heilbronn, Germany).

Multi-walled carbon nanotubes (MWCNT; purity of over 95 weight percents) were obtained from Cheap Tubes Inc. (Cambridgeport, Vt., USA).

C11000 copper alloy ingots (>99.90% Cu, maximum oxygen content 0.04 weight percent) were obtained from Scope Metals Group Ltd. (Israel).

Copper powder (99+, 325 mesh) was obtained from Dr. Fritsch GmbH (Germany).

Preparation and Determination of Mechanical Properties of Metallic Samples:

Copper-based melts were prepared as described herein and poured into a grey cast iron permanent mold and samples with the dimensions depicted in FIG. 1 were obtained. The mold was preheated to 200° C. and then the melt was poured at 1120° C.±10° C.

Mechanical properties (e.g., tensile strength, yield strength and elongation) were determined using ingots cut and machined to the standard specimen dimensions depicted in FIG. 2, and a Lloyd EZ50 Universal Materials Testing Machine (Lloyd Instruments), according to ASTM B 108-01.

In addition, hardness (HV₁₀) was determined using an FV-810 Vickers Hardness Tester (Future-Tech), as the mean of five measurements for each sample under a load of 10 kg for 10 seconds.

Thermal Conductivity Tests:

Thermal conductivity tests were conducted on 10 mm×10 mm coupons with a thickness of 5 mm, using an LFA 457 MicroFlash® laser flash analyzer under an argon atmosphere. The values presented herein are the average of 5 measurements of thermal diffusivity at each temperature from the ambient temperature up to 400° C. Values of thermal conductivity (W/(m·K) units) were calculated from the following equation:

k=α·ρ·Cp   (1)

wherein α (mm²/second units) is thermal diffusivity; ρ is copper density (gram/cm³ units) and Cp is the specific heat capacity of copper (J/(gram·K) units).

X-Ray Powder Diffraction Studies:

X-ray powder diffraction studies were performed using an X'Pert PRO X-ray powder diffractometer (PANalytical) with monochromatic Cu Kα radiation (λ=1.542 Å) operating at 40 kV and 40 mA. Diffraction patterns were measured and recorded at a 2θ range from 40° to 100°, using a step size and rate of 0.02° per 2 seconds.

Example 1 Effect of Nanocompounds on Properties of Electrolytic Copper Alloy

A 2 kg portion of C11000 copper alloy ingots was charged into a graphite crucible, melted and overheated to 1150° C. The melt was coated by a commercial protective flux and subjected to a standard refinement procedure.

0.15 gram of TiN nanoparticles with a crystallite size of 10-20 nm, 0.15 gram of BN nanoparticles with a crystallite size of 10-20 nm, and 0.2 gram of multi-walled carbon nanotubes (MWCNT) with an outer diameter of 30-50 nm and length of 10-20 μm were used for modification. These nanomaterials were mechanochemically treated with 3.5 gram of copper powder by high-energy ball milling (with a planetary ball mill) for 10 minutes. The obtained mixture was then subjected to cold pressing at a pressure of 18 GPa. The fabricated pressed tablet was added into the melt. After a holding time of 10 minutes, the melt was poured into a grey cast iron permanent mold, and mechanical properties were determined, as described in the Materials and Methods section hereinabove.

The obtained tensile strength results are presented in Table 1 and in FIG. 3.

TABLE 1 Mechanical properties for unmodified Cu alloy and exemplary Cu alloys modified with TiN or BN nanoparticles or multi-walled carbon nanotubes (MWCNT) Additive for Tensile Strength Elongation Hardness modification [MPa] [%] [HV₁₀] None 191.35 54.35 39.92 ± 2.20 MWCNT 230.41 50.53 53.44 ± 0.99 TiN 228.23 44.03 82.38 ± 4.06 BN 192.58 49.49 45.90 ± 1.37

As shown in FIG. 5, each of the tested nanocompounds enhanced the thermal conductivity of the Cu alloy throughout the entire tested temperature range (up to 400° C.). For example, the Cu alloy with 0.01 weight percent carbon nanotubes exhibited a thermal conductivity of 426.4 W/mK and 369.1 W/mK at 25° C. and 400° C., respectively; as compared with 306 W/mK and 249.2W/mK, respectively, for the unmodified Cu alloy.

According to the theory of thermal conductivity, electrons and phonons are the main heat carrying agents. Metal thermal conductivity is dominated by free electron movement. When thermal energy increases via increase of temperature, electron clouds begin to vibrate in the crystal structure of the metal, leading to the reduction of their free path; as the result, the thermal conductivity of the metal decreases [Tritt (2004), Thermal conductivity: theory, properties and application, Kluwer Academic/Plenum Publisher, New York].

In the copper-based samples described herein, thermal conductivity is expected to be dominated by the free electrons of the copper matrix, and would therefore be expected to be inhibited at copper-nanotube locations. The surprising increase in thermal conductivity of copper alloy observed upon addition of nanotubes may be attributed to the considerable length the nanotube, leading to efficient transport of heat relative to the copper matrix.

Evaluation of phase changes was performed using X-ray powder diffraction studies, according to procedures described in the Materials and Methods section hereinabove.

As shown in FIG. 6, modification with the tested nanomaterials did not affect the phase composition of the copper. All samples exhibited a copper cubic structure, according to powder diffraction file No. 01-071-3761.

These results indicate that the addition of various nanocompounds to copper-based materials enhances mechanical and physical properties of the material, while retaining control over the phase composition of the materials.

Example 2 Effect of Carbon Nanotubes at Various Concentrations on Properties of Copper Alloy

A 1.5 kg portion of C11000 copper alloy ingots was charged into a graphite crucible, melted in a Top 16/R laboratory furnace (Nabertherm GmbH, Germany) and overheated to 1150° C. The molten metal was coated by a PF-5 protective flux (Evtektika Ltd., Belarus), held for 5 minutes, and then subjected to a degassing process by introducing 0.75 grams of a PRM-10 degassing tablet (Evtektika Ltd., Belarus) to ensure removal of dissolved hydrogen and oxygen from the melt.

0.15, 0.3 or 0.45 gram of multi-walled carbon nanotubes (MWCNT) with an outer diameter of 30-50 nm and length of 10-20 μm were used for modification. These nanomaterials were mechanochemically treated with copper powder by high-energy ball milling with a PM 100 planetary ball mill (Retsch GmbH, Germany). The obtained mixture was then subjected to cold pressing at a pressure of 18 GPa. The fabricated pressed tablet was added into the melt. After a holding time of 10 minutes, the melt was poured into a grey cast iron permanent mold (preheated up to 200° C.) and samples with the dimensions depicted in FIG. 1 were obtained. The mold was preheated to 200° C. and then the melt was poured at 1120° C.±10° C.

Microstructural examinations of the specimens were carried out by BX53MRF-S optical microscope (Olympus, Japan) after etching by grain contrast reagent (NH₄OH:H₂O:H₂O₂ (3%), in a ratio of 1:1:2) equipped with image analysis software (Clemex, Canada). Electron microscopy images were obtained by MAIA3™ scanning electron microscopy (SEM) (TESCAN, Czech Republic) equipped with an energy dispersive X-ray spectroscopy (EDS) system (Oxford Instruments, UK) with an X-Max^(N)™ detector.

Because of the low density of carbon nanotubes (CNT) they would normally float on the melt surface.

As shown in FIGS. 7A and 7B, the mechanochemical treatment resulted in agglomerates of nanotubes (FIG. 7A) and individual nanotubes (FIG. 7B) being bonded to copper particles, as determined by electron microscopy.

These results indicate that mechanochemical bonding of copper powder to carbon nanotubes protects the nanotubes during incorporation into the melt and inhibits their movement towards the melt surface, thereby enhancing their presence in the bulk.

As shown in FIG. 8, addition of CNTs enhanced tensile and yield strengths of copper alloy at all CNT concentrations tested (0.01, 0.02 and 0.03 weight percent); with 0.01 weight percent CNT exhibiting the greatest enhancement in strength. In particular, the tensile strength and yield strength of copper alloy with 0.01 weight percent CNTs was 230.41 MPa and 59.22 MPa, respectively, versus 191.35 MPa and 53.94 MPa, respectively, for unmodified copper alloy.

Similarly, as shown in FIG. 9, addition of CNTs enhanced hardness of copper alloy at all CNT concentrations tested (0.01, 0.02 and 0.03 weight percent); with 0.01 weight percent CNT exhibiting the greatest enhancement in hardness, 77.29 HV versus 60.36 HV for unmodified copper alloy.

These results confirm that nanotubes can enhance mechanical properties of copper, and suggest that a high amount of nanotubes may induce agglomeration into the bulk at a degree which leads to increased stress in the metal.

As further shown in FIG. 8, addition of CNTs slightly reduced elongation, in agreement with the results presented in Example 1.

Modification with 0.01 weight percent CNT did not affect the phase composition of the copper alloy, as determined by X-ray diffraction, indicating that any new phases associated with the CNTs are at a sufficiently low concentration to be below the XRD detection limit.

Fractures surfaces of the copper alloy with 0.01% CNT was then analyzed by scanning electron microscopy.

As shown in FIG. 10A, numerous dimples were observed on the fracture surface, which are associated with ductile behaviour, and are attributed to the ductile nature of copper.

As shown in FIG. 10B, a broken nanotube was observed on the fracture surface.

As shown in FIGS. 11A and 11B, the microstructure of unmodified copper alloy (FIG. 11A) exhibited irregular, coarse and randomly oriented grains, with an average grain size of 103 μm, and porosity (which appears as dark spots) throughout the alloy; whereas the microstructure of copper alloy with 0.01% CNT (FIG. 11B) exhibited reduced average grain size (74 μm) and oriented dendrites, indicating crystal growth in preferred directions irregular, coarse and randomly oriented grains, with an average grain size of 103 μm, and porosity (which appears as dark spots) throughout the alloy.

Taken together, the above results indicate that the observed copper strengthening was associated with nanotubes being well-distributed throughout the modified specimens, wherein the branched and long structure of nanotubes in the bulk of the alloy leads to the inhibition of the dislocations movement, resulting in metal strengthening.

Example 3 Effect of Nanocompounds on Properties of Pure Copper

Pure copper was modified by addition of TiN nanoparticles with a crystallite size of 10-20 nm, or with multi-walled carbon nanotubes (MWCNT). The nanoparticles or nanotubes were mechanochemically treated by high-energy ball milling and then cold-pressed before being added to a copper melt, according to procedures described in Example 1. The copper melt for each sample was poured into a grey cast iron permanent mold. The properties of the modified and unmodified copper are compared, using procedures similar to those described hereinabove.

Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.

All publications, patents and patent applications mentioned in this specification are herein incorporated in their entirety by reference into the specification, to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated herein by reference. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present invention. To the extent that section headings are used, they should not be construed as necessarily limiting. In addition, any priority document(s) of this application is/are hereby incorporated herein by reference in its/their entirety. 

What is claimed is:
 1. A composition-of-matter comprising copper or an alloy thereof, and at least one nanocompound dispersed in said copper or an alloy thereof, wherein said copper or an alloy thereof is a cast metal.
 2. The composition-of-matter of claim 1, comprising a chill zone, a columnar zone and an equiaxed zone.
 3. The composition-of-matter of claim 1, wherein said cast metal is a sand-cast metal or a permanent mold-cast metal.
 4. The composition-of-matter of claim 1, wherein said nanocompound comprises a substance selected from the group consisting of an oxide, a nitride, a carbon nitride, a carbide and/or a carbon-based nanocompound.
 5. The composition-of-matter of claim 4, wherein said nanocompound comprises a substance selected from the group consisting of boron nitride, titanium nitride, titanium carbon nitride, titanium carbide, silicon carbide, tungsten carbide, aluminum oxide, titanium oxide, zinc oxide, aluminum diboride, and titanium diboride.
 6. The composition-of-matter of claim 4, wherein said carbon-based nanocompound comprises carbon in a form selected from the group consisting of diamond, graphite, graphene, and a carbon nanotube.
 7. The composition-of-matter of claim 1, wherein said nanocompound comprises a carbon nanotube and/or an inorganic nanotube, said nanotube being a single-walled or multi-walled nanotube.
 8. The composition of claim 7, wherein said inorganic nanotube comprises a compound selected from the group consisting of tungsten disulfide, molybdenum disulfide, niobium disulfide, tantalum disulfide, hafnium disulfide, titanium disulfide, cadmium sulfide, zinc sulfide, gallium nitride and boron nitride.
 9. The composition-of-matter of claim 7, wherein said nanotube is a multi-walled nanotube.
 10. The composition-of-matter of claim 1, wherein a concentration of said nanocompound in said composition-of-matter is in a range of from 0.001 to 1 weight percent.
 11. The composition-of-matter of claim 10, wherein a concentration of said nanocompound in said composition-of-matter is in a range of from 0.001 to 0.015 weight percent.
 12. The composition-of-matter of claim 1, wherein said nanocompound is characterized by an average diameter in a range of from 3 to 150 nm.
 13. The composition-of-matter of claim 1, having a tensile strength which is at least 10% higher than a tensile strength of a corresponding composition-of-matter without said nanocompound.
 14. The composition-of-matter of claim 1, having a yield strength which is at least 5% higher than a yield strength of a corresponding composition-of-matter without said nanocompound.
 15. The composition-of-matter of claim 1, having a hardness which is at least 10% higher than a hardness of a corresponding composition-of-matter without said nanocompound, under a load of 10 kg for 10 seconds.
 16. The composition-of-matter of claim 1, having a thermal conductivity which is at least 10% higher than a thermal conductivity a corresponding composition-of-matter without said nanocompound, at a temperature of 25° C. and/or 400° C.
 17. The composition-of-matter of claim 1, having an elongation which is at least 90% of an elongation of a corresponding composition-of-matter without said nanocompound.
 18. The composition-of-matter of claim 17, having an elongation which is at least 10% higher than a corresponding composition-of-matter without said nanocompound.
 19. A process for preparing a composition-of-matter comprising copper or an alloy thereof, the process comprising dispersing at least one nanocompound in a melt of copper or and alloy thereof, and cooling the melt.
 20. The process of claim 19, further comprising effecting mechanochemical mixing of said nanocompound and copper in a solid form prior to said dispersing nanocompound in said melt.
 21. The process of claim 20, wherein said copper in a solid form comprises a copper powder.
 22. The process of claim 20, wherein a weight ratio of said nanocompound and said copper in a solid form is in a range of from 1:1 to 1:300 (nanocompound: copper).
 23. The process of claim 20, wherein said mechanochemical mixing is effected by a ball mill.
 24. The process of claim 19, wherein said nanocompound comprises an oxide, a nitride, a carbon nitride, a carbide and/or a carbon-based nanocompound.
 25. The process of claim 19, wherein said nanocompound comprises a carbon nanotube and/or an inorganic nanotube, said nanotube being a single-walled or multi-walled nanotube.
 26. The process of claim 19, wherein said nanocompound is dispersed in said melt at a concentration in a range of from 0.001 to 1 weight percent.
 27. The process of claim 26, wherein said nanocompound is dispersed in said melt at a concentration in a range of from 0.001 to 0.015 weight percent.
 28. The process of claim 19, wherein said nanocompound is characterized by an average diameter in a range of from 3 to 150 nm.
 29. A composition-of-matter prepared according to the process of claim
 19. 30. An article of manufacture comprising the composition-of-matter of claim
 1. 